1. Field of the Invention
The present invention relates generally to a plate workpiece processing machine such as a shearing machine, and more specifically to a workpiece processing machine which can process a workpiece in high precision and at high speed.
2. Description of the Prior Art
In a shearing machine, for instance, before a long plate workpiece is cut off into a plurality of plates of a predetermined length, the workpiece is first trimmed at an extreme forward end thereof. In doing this, conventionally, a workpiece is pushed against a workpiece side surface positioning device so that the side edge thereof is brought into contact with a sidegage (side locating member) arranged on a lower frame in front of a cutter position; and then the workpiece is fed forward until being brought into contact with a trimming stopper member arranged at the back of the cutter position. After having confirmed that the workpiece is correctly positioned by the sidegage and the stopper member, a slide which supports an upper blade is moved downward to trim the workpiece.
In the prior-art method of trimming a workpiece, however, there exists a problem in that it takes much time to trim the workpiece at a correct position and further it is difficult to trim the workpiece accurately because the workpiece is easily dislocated from the sidegage or the trimming stopper member when or after the workpiece is fed forward.
After a workpiece has been trimmed, the trimmed workpiece is to be cut-off into a predetermined length. In the conventional method, a length of the workpiece to be fed forward extending from a cutter position is calculated on the basis of a workpiece position and the current workpiece feeding speed obtained through a servomotor. However, this method is inevitably complicated and costly and therefore requires sufficient maintenance.